Surveyor s leveling-rod



(No Model.)

G. B. STOWELL. SURVEYOBJS LEVBLING ROD.

No. 495,438. Patented Apr. 11, 1893'.

lIINDI-Fb` UNITED STATES PATENT OFFICE.

GEORGE B. S'IOWELL, OF SOMERVILLE, MASSACHUSETTS.

SURVEYORS LEVELING-ROD.

SPECIFICATION formingpart of Letters Patent No. 495,438, dated April 11, 1893.

Application filed J' une 24, 1892.

To all whom it' may concern;

Be it known that I, GEORGE B. STOWELL, a citizen of the United States, residing at Somerville, in thel county of Middlesex and State of Massachusetts, have invented a new and useful Leveling-Rod, of which the following is a specification.

My invention consists of an improved self reading and a combined self reading and target leveling rod.

The object of my improvement is a self reading or a combined self reading and target leveling rod which, though designed to slide out several feet longer, is still more concise, lighter and stiffer than any ofthe devices in present use. These results are obtained by the mechanism illustrated in the accompanying drawings.

Similar letters refer to similar parts in the dierent views.

Figure 1 is a perspective elevation of the closed rod, the face of which is inclined at an angle of about forty-five degrees from the line of vision so as to showv both the main members of the rod'. As indicated by the graduations several feet are cut away in the draw` ings. Fig. 2-is a similar elevation of the rod fully drawn out, unessential parts as before being cut away. Fig. 3 is a side elevation of the setting clamp A. Figa is across section of the rod (closed or extended) through the setting clamp A. Fig. 5 is a cross section of the closed rod near the top through the clamp I. Fig. 6 is a front elevation of the target B. on a section of the rod. Fig. 7 is a cross section 0f the rod through the setting clamp A. with the sliding target B. at that point. Fig. 8 is a perspective elevation of the combined target and self reading rod partially extended and the target B in sliding position.

The feature of first importance in a leveling rod is length. The longer the rod the better, provided it is not longer than can be conveniently handled or provided, rather, that in gaining the extra length, the advantage thereof is not off set by an addition of extra details of construction which make the rod too heavy and bungling to be practical.

My rod--as I design to build it-closes as shown in Fig. l. to six and five tenths feet and slides out as shown in Fig. 2 to sixteen Serial No. 437,846. (No model.)

the rod, is made (Fig. 2) six and five tenths feet long. The face is hollowed out, leaving raised edges-as shown in the cross sectionwhich receive the pressure and wear of the setting clamp A. and protect the graduations on the face of the rod.

E, is the first extension of the rod and extends when drawn out five feet above the top end of C. In the closed rod, E rests on a short block fof uniform section with itself fastened on the back side of the lower end of C. as shown in Figs. 1 and 2. Slide Elike member C is also constructed with raised edges or shoulders which preventits graduations from being defaced by rubbing against lC. The movements of slide E are guided and controlled by the clamps A. and G. It will be readily seen from the construction in Fig. 4.

compression between members C and slide E in virtue of which the motion of the latter may be arrested at any point.

Slide D, Figs. 2 and 5, is a new feature of my rod to which special attention is directed.

Previous attempts to increase the length of leveling rods by telescoping slides and other kindred devices have failed because in every case so far as I am aware they have hampered the rod with extra detail and weight offsetting all advantage of extra length and barring its general use. f

The device for a secon'd slideillustrated by D, Figs. 2 and 5, must commend "itself at once for in opposition to the above objections it adds to the rod a practical working length of four feet and eight tenths without noticeably increasing either its weight or size of section.

The construction and manner of working the extension D in a specially cut groove in the back of extension E. is fully illustrated by Figs. 2 and 5. rlhe extension D. is held IOO with the latter extension it will not be interfered with by guiding clamp G. Clamp G is made of two separate pieces of sheet brass fastened on opposite sides of member C. near the top. 'The two lips o f the clamp bend'over the back edges of E-an easy fit-leaving the latter free to slide. G is only a guide clamp for the extension E. and its operation is fully apparent from Figs. 1, 2 and 5.

The setting clamp A in most leveling rods is fastened to one or other members of the rod by screws in such manner that the repeated setting and loosening the clamp being reverse strains upon the screws whichsoon work them f loose in the wood and the clamp becomes rickety. v The latter evil is'neatly avoided in the clamp A shown-natural size-in elevation and cross section by Figs. 3 and 5. The elevation Fig. 3 shows a couple lugs 32j. which screwed to the member E and fitting loosely in the oblong slots in the sides of the clamp A bear no part of the strains exerted by the latter but merely cause it to. travel with the member E. The clamp having therefore a free lateral movement as regards both members of the rod,all the strains exerted by the f setting screw h, are distributed between the tinct for the leveler in looking through his telescope to himself read the elevation on the rod indicated by the cross hair in his instrument. This style ot' rod is distinguished from a target rod-so called-in that the latter is provided with a sliding index or target which the rodman moves up or down according to signals from the leveler until a special line or mark on the target is covered by the crosshair in the leveling instrument. The target is then clamped in its last position and its indicated elevation taken-usually by the rodman.

Target rods are usually provided with a Vernier, a device by which the elevations indicated by the target are taken to (theoretically) thousandths of a foot. Such accuracy is however unnecessarily fine for the great majority of field Work and, since it is attained at a great waste of time over that required for obtaining results sufficiently accurate with a self reading rod, there is a marked tendency among the truly practical engineers to a more and more general use of the latter. Since, however, there are occasions when a target is desirable I have, to adapt my rod to all emergencies, devised for it a target making the rod, if desired a combined self reading and target rod.

The slight additions to the rod as already described necessary to effect the combination are illustrated by Figs. 6, 7 and 8. The only difference between the rod cross sections as shown by Figs. 4 and 7 is that the raised shoulders on which lips fm m slide are in Fig. 7 deeper and cut beveling inside for reasons to appear later whereas in Fig. 6 the same shoulders are shallower and have straight edges.

The target consists of two blocks shown in cross section byoand o Fig. 7. These blocks are about four inches long. At right angles to their length and about one half inch from either end two brass tubes indicated by dotted lines Fig. 7 are fitted in the blocks. These tubes are permanently fastened in the block o which in t'urn is screwed to the back of the face B; but in block o the. tubes are an easy fit so as to allow the block to slide on them. A coil spring placed in each tube holds the blocks apart. When it is desired to attach the target to the rod the blocks o and o are pressed together and inserted between the beveled shoulders on the front of the rod Fig. 7. On relaxing the pressure of the fingers the blocks separate until they meet the raised beveled shoulders and the target is held in position on the face of the rod. To slide the target up or down the rodman simply compresses the blocks until friction is enough reduced to allow the target to be raised or lowered. When any desired position is reached the pressure is released and the target remains fixed. The coil springs acting as they do in the blocks, take the place of the usual extra clamp for settingthe target. l

In the target rod the face members C in addition to the regular feet and tenths of feet graduations has the tenths graduations subdivided into hundredths as shown on left side face of rod in Figs. 6 and 8. A Vernier plate, p. appropriately graduated, is fastened to block o Figs. 6 and 7, in such a manner that its lower or graduated edge just clears the one hundredths scale on O. and enables rod reading to be taken (theoretically) to thousandths of a foot. The manner of taking vernier reading not being new and being essentially the same in all instruments is not described here.

It will be observed Figs. 6 and 7 that the face of the target B. and blocks o and 0 are cut away in the center in such manner that the Vernier and on'e hundredths graduations on the rod can be readily seen through the opening in the target. The target is in correct position for taking readings when the horizontal hairin the leveling instrument covers the line r r on the target. The target slides on face of rod up to six and three tenths feet. With respect to higher readings it will be seen Fig. 8 that in the combination rod a 'piece fourtenths long is sawed off from member C and fastened to top end of member E in such manner that when the rod is closed the dissevered end occupies the same position in relation to member C as it did before it was separated from the latter. When it is desired to take higher readings than six and three tent-hs feet the target is slid up to that elevation (equals middle of above block) and set. As the target is now attached to member E. it is elevated to higher readings by IIO raising the latter slide which can be secured in any position by clamp A'. A second set of one hundredths graduations and Vernier is provided on the sides Of members E and C in such manner that continuous target readings can be taken up to eleven and threetenths feet.

I am aware that prior to my invention eX- tension leveling rods have been made. I therefore do not claim such broadly; b-ut- What I do claim as my invention, and desire` to secure by Letters Patent, is-

l.' In a combined self reading Or target levcling rod, the extension D, sliding in a specially cut groove in the back of slide E, in combination with slide C, clamps A, G, and I and blocks f, substantially as set forth.

2. In a combined self reading Or target leveling rod, the clamp Acomposed of set screw h, and friction disk i; lugs 31j. yand lips m. lm. all fastened tO and acting upon members E and O in combination with clamps G in the manner and for the purpose described.

3. In a combined self reading and target leveling rod, the target B, comprising blocks o and o', Vernier plate p, tubes and spiral springs Z. Z. in combination with members E n and C and clamp A, all as described vand the purpose set forth.

GEORGE B.- STOWE'LL.

for

W'itn'esses:

FRANK C. STOWELL, SIMON CONNOR. 

